System Size and Energy Dependence of Elliptic Flow

Abstract

The elliptic flow v2 is presented for the Cu+Cu collisions at sqrt{s_NN} = 62.4 and 200 GeV, as a function of pseudorapidity. Comparison to results for the Au+Au collisions at the same energies shows a reduction of about 20% in the flow observed for a centrality selection of 0-40%. The centrality dependent flow, expressed as a function of the number of participants N_part, is compared for the Cu+Cu and Au+Au systems using two definitions of eccentricity, the standard definition epsilon_standard and a participant eccentricity epsilon_part. The v2 / as a function of N_part, for the Au+Au and Cu+Cu collisions are consistent within errors, while v2 / gives unrealistically large values for Cu+Cu, especially for central collision.Comment: 3 pages, 3 figures, talk given at Particles and Nuclei International Conference (PANIC05), Santa Fe, New Mexico, 24-28 Oct 2005. Proceeding to be published by American Institute of Physic